Rice

Insect Management

Detailed Study of Insects

Rice Stem Borer

Scirpophaga incertulas (Pyralidae : Lepidoptera)

Rice stem borer is also commonly known as the paddy stem borer and yellow borer of rice. It is distributed in all Asian countries. It is a regular pest in all parts of India and in all districts of Andhra Pradesh. Seasonal occurrence It occurs both in kharif and rabi seasons in Andhra Pradesh. The pest affects the crop in the nursery, soon after transplanting and also in the pre-earhead stage. In case of late inter seasonal and the early second crops, the damage is done to the young transplants where in the case of late first crop and early inter seasonal crops, more damage is done at the earing stage.

Life history

• The female moth is bigger than the male and its forewings are bright yellowish brown with a distinct black spot in the center.
• The abdomen is wide, the tip being covered with tufts of yellowish hairs.
• The male moth is pale yellow - the abdomen is slender and the anal end has a thin hairy covering dorsally.
• Spots on the forewings are not conspicuous.
• The female moth lay eggs near the top of the leaf blade early at night in small masses covered with hairs and scales derived from the anal tuff.
• The ovi - position occurs upto 5 nights from emergence. The moths are short-lived and die 2 to 3 days after ovi - position.
• The fecundity of the moth vary from 100 to 150 eggs. The eggs are creamy white, flattened, oval and scale like. Egg period is 5 to 8 days.
• The first instar larvae are about 1.5 mm long and 0.5 mm wide. Pale yellow in colour with dark brown prothoraxic shield and orange head.
• Larvae crawl upward towards the tip of the plant during roaming period many larvae die.
• Remaining larvae descend towards the base of the plant and crawl between leaf sheath and stem.
• They enter into leaf sheath and feed on tissue for about a week and bore into stem through nodal region.
• In mature rice plants the catter pillars bore into the stalk region just below the ear head.
• Larval period lasts for 30 days.
• Pupation takes place inside the stem mostly in the lowest node of the plant, and just above water level
• In seedling stage, pupation take place in the root region .
• In single cropped areas mature larvae diapause in rice stubbles after harvest in December.
• Larvae pupate and emerge as moths after the monsoon rains.

Ecology

• Egg development takes place at about 16°C with an optimum temperature of 24 to 29°C and relative humidity of 90 to 100 percent.
• Hatching is drastically reduced at low temperatures of 13°C and relative humidity of 70 per cent.
• The rate of larval development is positively correlated to temperature range from 17 to 35°C.
• The threshold for pupal development is 15 to 16°C.

Nature and symptom of damage

Vegetative stage

• Larvae feed on green tissue of leaf sheath for 2 to 3 days.
• Bore into the stem at the nodal position and feed on inner tissue of plant. Under Severe conditions, it bores at the base and move upwards. Central leaf whorl does not unfold, turns brown dries off.
• Lower leaves remain green.

Heading stage

• Larvae bore at the peduncle node.
• White heads are the resultant effect.
• Damage is maximum at this stage.

Yield loss

• Early planted crop 1-19%
• Late planted crop 38-80%

Control measures

Cultural Methods

• Since the eggs are laid near the tip of the leaf blade, clipping the seedlings before transplanting reduces the carry-over of eggs from seed bed to the transplanted field.
• Harvesting at ground level or ploughing after harvesting remove majority of larvae and pupae.

Mechanical Methods

• The use of light traps was recommended earlier but now this method is not advocated as many beneficial insects are also attracted and killed.
• Use f Pheromone traps now a days the sex pheromones are utilized for mass trapping of male moths.

Biological Methods

Telenomus spp, Tetrastichus spp and Trichogramma Spp are identified as dominant complex stem borer egg parasitoids, they could not be utilized in a big way because of the limitations in mass rearing and releasing in our conditions. When these parasites are found in abundance the use of insecticides can be postponed.

• Resistant Varieties : Sasyasree ( RNR 446 ), Rathna and Kaveri were observed tolerant to this pest in Andhra Pradesh.

Chemical Methods

• Several chemicals were reported effective for control of stem borer, chemical control may be practiced without relying on only one chemical considering the cost, availability and safety to natural enemies.
• ETL recommended  5% dead hearts or 1% white ear or one egg mass or one adult /Sq.mt. (Recommendation based on growth of the crop) Nursery.
• Carbofuran 3G @ 42 Kg/ha or Phorate 10 G @ 12.5Kg /ha to be applied 7 days after germination of seed or spraying of Monocrotophos 1.6 ml or Chlorpyriphos 2.5 ml/li or Quinalphos 2ml/li at 10 days interval starting from 7 th day after germination.

Main Field

• Transplanting to panicle initiation
• Carbofuran 3 G @ 25 Kg/ ha OR Spraying of Monocrotophos 1.6 ml, or Chlorpyriphos 2.5 ml OR Quinalphos 2.5 ml or Carbaryl 3 gms or Phosphomidon 1 ml/ lit water.
• Panicle initiation to booting:
  • ETL: 1 moth / Sq.mt. Carbofuran 3 g @ 25 Kg / ha OR Spraying of Monocrotophos 1.6 ml or Chlorpyriphos 2.5 ml OR Quinalphos 2.5 ml or carbaryl 3 gms or Phosphomidon 1 ml/ lit. of Water.

Post flowering

• Spray Monocrotophos 1.6 ml or carbaryl 3 gms. OR Phosphomidon 1 ml or Cartap hydrochloride at 2 ml/ lit of water to be sprayed OR Cartap hydrochloride 4 G granules @ 20 Kg / ha to be applied.

Leaf Folder

Cnapholocrocis medinalis (guenee)
Lepidoptera : Pyralidae

The rice leaf folder, earlier considered as a minor and sporadic pest of rice in many Asian countries, appears to have become increasingly important with the spread of high yielding rice varieties and accompanying changes in cultural practices. It is distributed in many rice growing countries like India, Pakistan, Bangladesh, China, Burma, Bhutan, Indonesia, Japan, Nepal, Malaysia, Kerala, Vietnam, Srilanka, Taiwan, Thailand, Afghanistan and Australia etc.

• In India it is a serious pest in Andhra Pradesh, Madhya Pradesh, Orissa & Tamilnadu.
• In Andhra Pradesh it is distributed as a major pest in all rice growing districts particularly Krishna-Godavari delta, Khammam, Nagarjuna sagar project area.
• Nellore district is also experiencing more out breaks.

Seasonal Occurance

• The pest is reported throughout the year although they are most abundant during wet season.
• Infestation usually occurs during late growth stages of the crop.

Life History

Each female moth may lay about 300 eggs during its life time in singles are rows parallel to mid rid of both sides of young leaves. Incubation period varies from 3-6 days. Hatched larvae are white translucent in colour with light brown head initially - later body of larvae turn green. Larvae crawls to the base and feed on young unopened leaves.

• Second instar larvae migrate to older leaf and folds the leaf.
• Five larval instars are reported.
• Full grown larvae is 16 mm long and yellowish green in color with a dark brown head and prothoraxic shield.
• Mature larvae jump or wriggle rapidly   Larval period is 15   20 days.
• Pupation takes place inside leaf folder and pupae are slender and brown in color   pupal period is 6-8 days.
• Adult moth - yellow brown in colour   10-12 mm long.
• Fore wings have three dark oblique lines and hind wings have a broad anal area.
• Female attracts its male with a pheromone.
• Adults live about for a week and hide on host plant during day time.

Ecology

• High humidity and optimum temperatures are conducive factors for the rapid multiplication of the pest.
• The larval period is significantly prolonged when the larvae are reared on leaves of rice plants at the ripening stage.

Nature and Symptoms of Damage:

• The larvae fold the leaves and scrape the green tissues of the leaves from within and cause scorching and leaf drying.
• Each larva destroy several leaves by feeding.
• In severe infestations, each rice plant may have several rolled leaves which restricts photosynthetic activity.
• At 17 to 26.% of leaf damage the loss in yield vary from 16 to 21%.

Control Measures

Cultural

• Avoid close planting and application of more nitrogenous fertilizers, as close crop growth and heavy manuring are conducive for leaf folder activity.
• Sufficient quantities of Potassic fertilizers are to be applied to reduce infestation.
• Grow varieties with high silica content.

Mechanical

• Pass a thorny brush or a rope across the crop in vegetative phase to unfold the leaves and to expose the larvae to insecticidal application.

Biological

• Trichogramma japanicum and Copidosomopsis nacoleidae were recorded as important egg parasitoids.
• Trichomma cnaphalocrosis as larval parasite and Xanthopimpla flavolineata and Tetrastichus ayyari as pupal parasites were reported to suppress the pest.

Chemical Control

Spraying of Monocrotophos, 1.6ml, Chlorpyriphos 2.5ml or Quinalphos 2.5ml or Acephate 1gm or Carbaryl 3gm or Cartap hydrochloride 2gm/lit of water to be sprayed two times at 10days interval or apply cartap hydrochloride 4G. 10kg /acre.

• Since larvae feed by hiding in leaf folds the insecticide do not contact larvae.
• So care has to be taken to unfold the damaged leaves before spraying for effective control.

Economic threshold level (ETL)

• One damaged leaf/hill during planting to pre-tillering period 1 to 2 freshly damaged leaves/hill during mid-tillering to booting period.

Gundhi Bug

Leptocorisa oratorius
(Hemiptera : Alydidae)

Gundhi bugs are also called stink bugs as a characteristic foul odour is produced by scent glands present on the abdomen. These stink bugs are distributed in all the tropical and sub-tropical regions. In India and in all rice growing areas and in Andhra Pradesh.

• Its occurrence was observed in all the districts.
• In Chittoor district its out breaks were recorded in recent years.

Seasonal occurrence

• The population build up is usually noticed at the end of rainy season and declines rapidly during dry months when temperatures are unfavorable.
• The maximum population is usually observed during September to November months.

Life History

• The adult bug is long and slender and measures about 16-19 mm long.
• Diurnal in habit but active during early morning and evening.
• Bugs fly short distances   Females are stronger fliers.
• Female lay 250-300 eggs in two or three straight rows along side mid rib on upper surface of leaf blade.
• Eggs are disc shaped, dorsally flat and elliptical.
• Incubation period is one week.
• Bugs complete 1 or 2 generations on grasses and then migrate to rice fields.
• Newly hatched nymphs are green but turn brown as they grow.
• Nymphs feed gregariously until the fourth instar.
• Nymphal period varies from 25-30 days with 5 instars.

Ecology

• All the stages of the pest are vulnerable to changes in temperature and humidity.
• Favourable conditions: Temperature 27 -  28 ° C Relative Humidity 80-82%
• Flowering stage warm and cloudy weather and frequent drizzles favour population build up.
• Heavy rains reduce population.
• Extensive weedy areas near rice fields and staggered rice planting favour high population.

Nature and symptoms of damage

Both nymphs and adults suck sap from the grain at the milk stage. Damage by nymphs is more compared to adults. Unfilled or partially filled grains with a black patch on effected grain. Average incidence   5 to 10 %, Severe - 40-60 %.

Control Measures

Cultural control

• Removal of weeds in the vicinity of paddy crop as the pest breeds on a variety of grasses prior to its migration to rice crop.

Mechanical control

• Collection of the bugs by hand netting is suggested. Sweeping of rice plants with winnows smeared with sticky material like castor oil.

Chemical control

• Spraying of Monocrotophos 1.6 ml or Endosulfan 2 ml per litre of water once at flowering and another at grain hardening stage or dusting of Endosulfan 4 % or Carbaryl 5 % @ 25 kg/ha in evening hours.
• If needed application has to be repeated after 10 days.

Economic threshold level (ETL)

• 1 or 2 bugs/Sq.mt or per hill.

Green Leaf Hopper

Nephotettix virescens (distant)
Homoptera : Cicadellidae

The leaf hopper gained economic significance as regular pests of rice. The leaf hoppers attack all the aerial parts of rice plant. This pest is distributed in Bangladesh, Burma, Hongkong, Indonesia, Malaysia, Pakistan, Philippines, Taiwan and India. In India it is severe in Andhra Pradesh, Madhya Pradesh, Orissa and moderate to low in other rice growing states. In Andhra Pradesh it is found in all the districts where rice is grown.

Seasonal occurrence

• Leaf hoppers move from one rice crop to another rice crop and during intervening periods they feed and breed on grasses found in rice ecosystem.
• The hoppers remain active the year round.
• In general two population peaks can be observed one in first crop season and the other in second crop season.
• The insects are usually more abundant during dry season than during wet season.

Life History

• The pre-mating period ranges from one to two days.
• Eggs are laid in small slits made in soft parts of the plant.
• The number of eggs in a batch seldom exceeds 30.
• The incubation period is 6 to 12 days.
• The nymphal period lasts for 14-37 days.
• Rice plants at tillering and panicle initiation stage are more favourable for the rapid build-up of pest population.

Ecology

• The abundance of Green hoppers has been correlated to high temperature, low rainfall and abundant sunshine.
• The rate of nymphal development is faster at high temperatures. (14.1 days at 35 ° C and 37.3 days at 20 ° C).
• The rapid build up of pest population was observed at tillering and panicle initiation stages of rice crop.
• The insect can withstand long periods of starvation. They are highly attracted to light at nights.

Nature and symptoms of Damage

The nymphs and adults cause direct damage to rice crop by sucking sap from leaf sheaths and blades. The feeding marks predispose plants to fungal and bacterial infections. The affected leaves and plants turn to yellow colour and growth is retarded. They indirectly act as vectors by transmitting virus diseases such as Tungro and Yellow dwarf. They also feed on some grasses like Cynodon dactylon, Echinochloa crussgalli and Eleusine indica, etc.,

Control Measures

Cultural Methods

• Avoid excess application of nitrogenous fertilizer.
• Maintain weed free field bunds.

Biological Methods

• A number of predators like Lycose Pseudoannwlata on nymphs and adults, Cyrtorlinus lividipennis on eggs and nymphs and parasites like Tomosvaryella spp and Pepunculus spp on nymphs and adults were reported as important against green leaf hopper.
• But their rearing and practical application is not practiced.
• Minimum insecticidal use was suggested when these natural enemies are in good numbers in rice fields.

Chemical Control

• Since green hoppers are vectors of virus diseases, use of insecticides having immediate knock down effects are preferred.
• Soil application of Carbofuran granules into the root zone at the time of planting or few days after planting helps in controlling Tungro virus by preventing feeding of Jassid vectors.
• Seedling root dip in 0.02 @ Chlorpypiphos solution for overnight (12 hours) was recommended not only for this pest but also to other rice pests.
• In case of time shortage addition of 1 % urea to insecticide emulsion is suggested in which case root dip time can be reduced to 3 hours.

Nursery

• Carbofuran 3 G @ 42 kg/ha or Phorate 10 G @ 12.5 kg/ha to be applied 7 days after germination of seed. Or
• Spraying of Monocrotophos @ 1.6 ml or Chlorpyriphos 2 ml or Quinolphos 2.5 ml per litre of water, at 10 days interval starting from 7 th day of germination.

Main field:

• Soil application of Carbofuran 3 G @ 25 kg/ha in the last puddling or at 10 days after transplanting keeping 1-2" of water level. Or
• Foliar application of Monocrotophos 2 ml or Chlorpyriphos 3 ml per litre of water at 10 day interval starting 10 days after planting.
• If population is more for immediate knock down affect combination of Monocrotophos 2.0 ml with dichlorophos 1 ml/litre of water is recommended.
• Ethofenprox 10 EC at 1.5 ml or BPMC 50 EC at 2 ml/lit also are recommended at foliar sprays.

Planting to Pre-Tillering, Mid-Tillering & Panicle Initiation & Booting	Foliar application of Carbaryl, Phosalone, Phosphomidon @ 0.5 kg a.i./ha or Cartap WP @ 300 g a.i./ha. Ethofenprox EC @ 75 g a.i./ha or Granular application of Carbofuron @ 0.75 kg a.i./ha or Phorate @ 1.25 kg a.i./ha or Fipronil @ 0.75 g a.i./ha.
Planting to Pre-Tillering	Spray Monocrotophos, Carbaryl, Phosalone, Phosphomidon @ 0.5 kg a.i./ha or Cartap WP @ 300 g a.i./ha, Ethofenprox EC @ 75 g a.i./ha or apply Carbofuran granules @ 0.75 kg a.i./ha or phorate granules @ 1.25 kg a.i./ha or Fipronil granules @ 0.75 g a.i./ha.
Mid-Tillering	As recommended above.
Panicle Initiation to Booting	As recommended above.

Economic threshold level(ETL)

Planting to Pre-Tillering	2 insects/hill in Tungro endemic area. 10 insects/hill in other areas.
Mid-Tillering, Panicle Initiation to Tillering	20 insects/hill

Brown Plant Hopper

Nilaparvata lugens (STAL)
Homoptera : Delphacidae

The brown plant hoppers are one of the most serious pests of paddy having become increasingly important in recent years. They are distributed throughout South and South Asia in the early 1970s. In India the pest was reported as a major one in states of Kerala, Karnataka. Tamilnadu, West Bengal and Andhra Pradesh.

• Outbreaks have coincided with large scale release and cultivation of high yielding varieties.
• They spread rapidly in high tillering varieties producing thick stands, fields where excessive nitrogenous fertilizers are used, fields which are continuously flooded and in areas where continuous cropping of rice is practiced.
• The BPH problem is noticed in all rice growing areas of Andhra Pradesh.

Seasonal occurrence

• The seasonal prevalence of the pest is mostly dependent on the availability of host plants.
• In warm and humid tropics pest remain active throughout the year.
• The pest usually occurs in August-September with peak numbers in October and November and again in February and March in India.

Life history

• Insects have a brown body and chest nut brown eyes.
• Adult measures 4.0   4.5 mm in length - Two types:
• Large sized wings not fully developed (Brachypterous)
• Fully developed wings extend beyond the length of the body (Macropterous). These migrate and colonize in new fields.
• Settled colonies produce next generation   Females developed as Brachyupters and make as macropters.
• Adult emerge at the base of the stem   mate on the day of emergence.
• Brachypters lay 300-350 eggs and Macrophers lay less no. of eggs   in straight line on the leaf sheath in groups of 2-12. Red eye spot appear on one end of the egg.
• Eggs hatch in 6-9 days   Nymps under 4-5 instars and become adults in 10-15 days   longevity of adults vary from 18   20 days.

Ecology

• High humidity and warm temperatures are favorable for build up of the pest.
• The insect prefers irrigated wet land fields to upland rice.
• The hatchability of eggs and survival rate of nymphs are maximum around 250C. With in a range of 28 to 30 ° C.
• The population fluctuates according to availability of post plant, activity of natural enemies and environmental factors.
• High nitrogen application leads to faster insect development.

Nature and symptoms of damage

• Nymphs and adults congregate at the base of plants, above water level, and suck plant sap.
• In severe infestation the leaves first turn yellow, and later brown and finally the affected plants dry and die.
• The first sign of damage is the sudden slumping of crop in patches in the field.
• The crop in these affected patches dries up giving a scorched appearance called  Hopper-burn.
• Crop drying in patches giving scorched appearance.
• Crop loss is usually considerable and complete destruction of crop occurs in severe cases.

Control measures

• Adopt planting with formation of alleys of 25 cm at intervals of 2 Mts to provide good aeration and sunlight.
• Avoid dense planting. Planting of 33 hills in kharif and 44 hills in Rabi
• Per Sq.mt may be followed.
• Excess application of N fertilizers may be avoided.
• In vegetative phase of the crop growth periodical drying and wetting may be followed for short period to create disturbance in micro climatic conditions favorable to pest development.
• Grow resistant varieties like Chaitanya, Krishnaveni, Chandan, Triguna, Deepthi, Nandi, Vijeta, Pratitha, Vajram etc.
• In developing resistant varieties bio type development has complicated the effectiveness, sources resistant in one region may be susceptible in an other region. The susceptibility of IR 26, the first brown plant hopper, resistant variety released by IRRI in India signaled the evolution of bio types among hopper populations.

Biological control

Egg parasites like Angrus spp, and nymphal and adult parasites like Pseudogonatonus spp, were observed to exercise control to the extent 10 to 40%. Mirid bugs, Cyrtorlinus lividipennis, is one of the most important predator of BPH in rice ecosystem. It provides both eggs and nymphs.

• The wolf spider, Lycose Psewdoannulata and some lady beetles and water bugs were observed as potential predators are found in abundance in rice ecosystem avoid chemical application and conserve natural enemies.

Chemical Control

• Application of Carbofuran 3G @ 25 Kg/ha or spraying of Monocrotophos 36% EC 2.2 ml or carbaryl 50%WP 3 gm or Ethofenprox 10 EC at 1f.5 ml or BPHC 50 EC at 2 ml or chlorpyriphos 20 EC at 3 ml per litre of water were found effective.
• At the time of milky stage if needed dust Carbaryl 5% @ 25 Kg/ha.

Planting to Pre-Tillering	Spray Carbaryl 0.75 Kg a.i./ha Monocrotophos, Phosolone, Phosphomidon Or BPHC @ o.5 Kg/ha or Fiprinol SC @50 gm a.i./ha or Ethofonoprox EC @75 Gm a.i./ha or apply Carbofuran granules @ o.75 Kg a.i./ha or phorate granules @ 1.25 Kg a.i./ha or Fiprinol granules @ 75 gm a.i./ha.
Mid-Tillering	As recommended earlier.
Panicle Initiation And Booting	Preferable apply Carbofuran @ 0.75 kg a.i./ha or Phorate granules @ 1.25 kg a.i./ha or Fipronil granules @ 75 gm a.i./ha or spray as recommended earlier.

Economic threshold level(ETL)

• ETL - Use of appropriate insecticide at the Economic threshold level (ETL) places pest control on a sound economic basis with minimum ecosystem disruption.
• ETL for BPH - 5 to 10 insects/hill.

Asian Gall Midge

Orseolla oryzae (wood - mason)
( Diptera : Cecidomyiidae )

The gall midge is primarily a pest of low land irrigated rice but has been reported in upland and deep water rice also. The extent and severity of gall midge infestation has significantly increased since 1970s. The cultivation of high tillering varieties, intensive management and low parasitization are conducive to the rapid multiplication of this pest. It is distributed in almost all rice growing Asian countries. In India it occurs as a serious pest in Madhya Pradesh, Manipur, Orissa, Andhra Pradesh, Bihar, Karnataka and Kerala.

• In Andhra Pradesh its out-breaks were noticed in Khammam, Sreekakulam, Vizag and Vijayanagaram districts.
• About three bio-types were identified in Andhra Pradesh.

Seasonal occurrence

• The gall midge attacks rice crop from the nursery to the end of tillering stage.
• The pest remains inactive as a pre-pupa in wild rice or weeds during dry season.
• At the onset of monsoons, it becomes active and completes one to two generations on grasses before it moves to rice crop.
• The incidence is usually high during months of July and August during which period the maximum tillering takes place.
• Young maggots can not survive in plants that pass the vegetative stage as there are no actively growing apical buds for them to infest.
• In some cases, the pest survives on weeds and also in rice stubbles left after the first crop.
• In multiple-cropping areas the fly seldom infests the second crop.
• Five to Eight overlapping generations were reported in one season.

Life History

• Adult gall midge is similar to female mosquito in appearance.
• Soon after emergence moulting take place
• Female flies mate only once.
• Eggs are laid in singles or groups on the under side near the base of the rice leaf or on leaf sheath.
• Single female is capable of laying 100   200 eggs.
• Adults are nocturnal in habit and attracted by light.
• Male mostly die in 12-18 hours after emergence   while female live for 3 days.
• Eggs are shinning white or pinkish, red or yellow in colour   elongated tubular and measures 0.55 mm long.
• Eggs turn to amber colour before hatching   incubation period ranges from 3-4 days.
• Newly hatched maggots are grey white and fairly stout with a pointed anterior end.
• Larval period is 15-20 days with 3 larval instars.
• Pupation takes place inside the galls near the base of the plant.
• Pupae have abdominal spines which enable it to wriggle its way to the tip of gall.
• Pupal period varies from 2-8 days .
• Adult emergence generally takes place at night or early morning.
• Entire life cycle takes about 25-38 days.

Ecology

• The pest requires high humidity for proper development and hatching of eggs.
• The favorable condition for fly development is 26 to 300C and 82 to 88 % relative humidity.
• Heavy rains or storms cause high mortality.
• Early monsoon rains, late planting, prolonged cloudy weather, continuous heavy rains during July to September were found favorable for rapid development of the pest in Andhra Pradesh.

Nature and symptoms of damage

Damaged tillers turns into tubular galls which dry off without bearing panicles. Main external symptom is SILVER SHOOT or GALL which resembles onion leaf. Fully developed gall is a silvery white hallow tube 1 cm wide and 10   30 cm long. Attack to rice seedlings leads to profuse tillering and these new tillers often become infested. Pests starts infestation from seed bed to booting stage in main field. Larvae develop only on growing primordia. Yield loss is 0.5% for every unit percent increase in incidence. Three bio types are noticed in India   Which are capable of damaging cultivars, resistant to other populations of the same species.

Control Measures

Cultural

• Adopt early planting adjust planting time so that tillering is completed before 15th August.
• Grow resistant varieties like Pothana, Divya, Kavya, Yerramallelu,Kesava, Oragallu, Badrakali, Siva, Rudrama, Varsha, Surekha,palguna.
• Several workers observed that cultivars with high levels of resistance to gall midge received no benefit from insecticidal treatment.
• Avoid dense planting which increases population.
• Removing weeds like Echinochloa colonum, Leersia hexandra, Cynodon dactylon and Panicum miliaceum etc., which are alternative hosts to maintain field sanitation.
• Avoid excess irrigation.
• The pest tends to do more damage and increase in number with excess fertilization of nitrogen.
• Use only recommended doses of Nitrogenous fertilizer.
• Uprooting stubbles with deep ploughing soon after harvest is recommended to avoid hiding larvae.

Biological Control

• Platigaster spp is more active in months of October-November and suppresses the gall midge by parasitization.
• Chemical control Dusts and spray formulations are not very effective against gall midge.
• So granular application of insecticides is preferred.
• Seedling root dip in Chlorpyriphos also helps in preventing early infection.

Nursery	Apply Carbofuran or Phorate @ 1kg to 1.25 kg a.i./ha or spray Monocrotophos @ 0.5 kg a.i./ha or Carbaryl 0.75 kg a.i./ha. In endemic areas adopt seedling dip with Chlorpyriphos.
Planting to Pre-TilleringMid-Tillering	Apply carbofuran 0.75 kg a.i./ha or Phorate, Quinolphos or Isazophos granules @ 0.6 kg a.i./ha or Fipronil granules @ 0.75 g a.i./ha.

Economic threshold level (ETL)

Nursery	One Silver Shoot / Sq.mt.
Planting to Pre-Tillering	One gall /m2 (endemic areas) or 5 % affected tillers (Non-endemic areas).
Mid-Tillering	5 % affected tillers.

Hispa

Dicladispa armigera (oliver)
(Coleoptera : Chrysomelidae)

This pest was reported to cause considerable crop losses in many Asian countries. It was observed to cause heavy losses even to the extent of 55% in Bangladesh. It is common in wet-land environments and sporadic out breaks have been reported from many parts of India. In Andhra Pradesh it is observed as occasional pest in certain parts of rice growing districts.

Seasonal occurrence

• The pest usually occurs from July to October.

Life History

• Adults are small shiny black beetles of 5.5 mm long with spines on their wing covers Longevity of female - 20 days and male - 15 days
• Beetles mate 3-4 days after emergence
• Female beetles lay eggs in singles with in the epidermal layers of the ventral surface of rice leaves.
• Newly hatched grubs are pale yellow in color and 2 to 4 mm long.
• Larval stage last for 7-12 days
• Pupae are flat, brown and exarate - pupal period last for 4-5 days
• Adult beetles cut their way out from rice leaf and become internal feeder.

Ecology

• High humidity after rains and intermittent bright sunshine appears to favor Hispa development in South India.
• Heavy rainfall in July followed by unusually low rainfall in August and September was characteristic of epidemic years.
• The late planting in August suffers severe damage with little chance of recovery.

Nature and symptoms of damage

Both grubs and adult beetles feed on rice plants. Adults scrape chlorophyll first between the veins and the lamina. White parallel streaks on the leaves. Feed on veins also resulting in the formation of blotches on the leaves. In severe infestations the affected leaves turn to brown and the field presents a dried-up appearance. It was reported that a single adult beetle consumes about 25 m2 of leaf area in a day. A single grub was found to consume, on an average 123.4 mm2 of rice leaf in its life time.

Control Measures

Cultural

• Grasses like Cynodon dactylon, Echinochloa colona, Echinochloa crussgalli etc., were found as alternative hosts.
• Hence field sanitation has to be adopted with timely weeding both in the field and on bunds.

Mechanical

• Sweeping rice plants with winnows coated with sticky materials may help to some extent in suppressing adult population.
• A rope soaked in kerosene and held by two men can be brushed across the foliage to kill Hispa beetles.
• The degree of control however, with this method is minimal.
• Clipping of tops of seedlings prior to planting removes not only Stem borer eggs but also Hispa eggs.

Chemical

• Spraying of Monocrotophos 1.6 ml or Chlorpyriphos 2 ml or Phosalone 2 ml or Carbaryl 3 gms/litre of water.
• Ethiphenphos EC @ 7.0 g a.i./ha or Fipronil; SC @ 50 gm a.i./ha or apply Carbofuran granules @ 0.75 kg a.i./ha.

Economic threshold level(ETL)

• Planting to pre-tillering stage : 1 adult or 1 damaged leaf/hill.
• Mid-tillering stage : 2 adults or 2 damaged leaves/hill.

Climbing Cutworm

Mythimma separata (walker)
(Lepidoptera : Noctuidae)

The climbing cut worm other wise known as Rice Ear-eating caterpillar is a minor pest until recently, has become a serious pest in India. It is distributed in all rice growing Asian countries with major status in Bangladesh and China. In India, it is found to cause considerable damage in Andhra Pradesh, Orissa and Uttar Pradesh. Occasionally it was found to cause heavy damage to the crop in Andhra Pradesh.

Seasonal occurrence

• The pest has 3-4 generations a year. Adults appear in rice fields from May onwards and become active from July and November.
• The pest occurs in all rice environments but is most abundant in upland and rainfed wet land environments.

Life History

• The adult is a stout, pale red to brown coloured moth which measures 20 mm long with a wing expansion of 40mm.
• Moths feed on nectar from flowers and honey dew secreted by Homopterian insects.
• The female moths start egg laying in three days in batches of 100 between leaf sheath and stem.
• Newly laid eggs are spherical, greenish white, later turns to pale yellow and finally black before hatching.
• The egg period varies from 5 to 7 days.
• Hatched caterpillars are dull white, and later turn to green with the orange or brown head.
• Four longitudinal light grey to black stripes run along the body.
• The larvae are nocturnal in habit they hide in loose soil, under trash, in stubbles, in leaf sheaths and in whorls.
• During night, they become active and feed on foliage.
• The larval period lasts for about 28 days with 5 to 6 instars.
• Pupation takes place in the soil. Sometimes naked pupae are also observed among the tillers. The pupal period is 8   11 days.

Ecology

• Heavy rains after a long drought often result in wide spread oviposition and larval development.
• Plants with dense foliage coupled with heavy tillering are mostly susceptable.
• Heavy application of nitrogenous fertilizers also favors the development of pest, because of the succulence of the plants.

Nature and symptoms of damage

The early instar caterpillars feed on green leaves lemma and palea of the developing grains as well as anthers of flowers. Mature larvae, become gregarious and feed voraciously on young leaves at night. The final instar larvae cut off rice panicles from the peduncle. In severe infestations the losses may go upto 60 % or even more.

• The pest also feeds on Sorghum and Maize besides feeding on several weeds like Cynodon dactylon, Cyperus rotundus, Echinochloa colona etc.,

Control Measures

• There are no effective biological methods of control to this pest except removal of alternative hosts in the vicinity of rice fields and harvesting at the ground level.

Chemical control

• Spraying of Monocrotophos at 1.6 ml or Endosulfan 2 ml or Chlorpyriphos 2 ml along with 1 ml of dichlorophos per litre during evening hours after giving irrigation.
• Spray thoroughly with Chlorpyriphos, dichlorophos, Endosulfan or Monocrotophos @ 0.5 kg a.i./ha during afternoon hours.

Economic threshold levels (ETL):

• 4 to 5 larvae/sq.meter or 1 larvae/hill.

Rice Case Worm

Nymphula depunctalis guen
(Lepidoptera : Pyralidae)

The rice case worm is an important pest of irrigated and rainfed wet land rice in South and Southeast Asia. Besides rice it infests various other grasses and millets. The pest occurs regularly in low populations, but sporadic increases in population result in intense defoliation of plants. It is existing in low population in all rice growing areas of Andhra Pradesh.

Seasonal occurrence

• In South India, moth population reach two peaks, one during November to December and another during May to June.
• These peaks coincide with periods of high rainfall and high humidity.
• Beyond November, they migrate to grassy areas.

Life history

• The adult moths are white in color & about 6 mm long with a wing expansion of 15 mm.
• They live for 4 to 8 days. Males mostly die after mating while females live longer.
• Eggs are laid in one or two adjacent rows in batches of 10 to 20 on the lower surface of leaves or on the leaf sheath near the water surface.
• The average fecundity of female moth is about 50 eggs.
• The eggs are circular with light yellow colour. But before hatching the eggs turn to dark colour with two purplish dots representing the eyes of developing larva.
• The egg period vary from 2 to 6 days.
• The newly hatched larva is pale green and measures 1.2 mm long.
• Larval period is 20 days with 5 larval instars.
• The larva starts feeding shortly after hatching and in about 2 days it begins to enclose itself in case made from the leaves.
• Feed on the leaves while remaining in case.
• full-grown larva attaches its leaf case to the rice stem slightly above the water level, closes the upper and lower ends of the case and undergoes pupation.
• The pupa is about 5.5mm long cream coloured and later turns to silvery white.
• Pupal period is about a week.
• EcologyVariations in temperature have no relationship with pest population.
• Infestation is more on heavy tillering and high yielding varieties.

Nature and symptoms of damage

The pest attacks the crop in the early transplanted stage. The leaf blade is cut into small bits and a tubular case is constructed by larva. The larva feeds by scraping under surface of the leaf blade.

• Upper epidermis surface of the leaf is intact
• White patches are seen on the leaf blades.
• Tillers become stunted and loose their vigour and often the plants are killed.

Control measures

Cultural control

• A rope may be passed over the young crop for dislodging the larval cases from the tillers and then the water may be drained for eliminating them.

Chemical control

• Drain water from the field and spray Endosulfan, Monocrotophos or Carbaryl @ 0.5 kg a.i./ha or dusting may be adopted with Carbaryl @ 30 kg / ha.
• Economic Threshold Level: 1-2 cases/hill

Whorl Maggot

Hydrellia spp (Diptera: Ephydridae)

Several species of Hydrellia exist in Rice ecosystem . The pest occurs in India, Bangladesh, Indonesia, Taiwan, Thailand and Phillippines. The pest is more abundant in Rice crop grown with continuous standing water. In AP it is found as occasional pest in Rice fields.

Seasonal occurrence

• It is usually found from August to October months in Andhra Pradesh.
• The pest is abundant during early stages of crop growth.
• The infestation ceases at the panicle emergence stage.

Life History

The adult flies are dull-grey coloured. The female fly measure 1.8 to 2.3 mm long.

• Cylindrical and whitish coloured eggs are laid singly on either surface of the leaves.
• The incubation period ranges from 2 to 6 days.
• Newly hatched maggots are transparent to light cream in colour and later turn to yellow.
• Maggots migrate to un open central leaves and remain there during entire larval period.
• The full-grown larva is cylindrical in shape with posterior end tapering to a pair of pointed spiracles.
• It measures about 7 mm long.
• The larval period is about 10 to 12 days.
• Light to dark brown, pupa and measures 4 to 5 mm long   pupates outside feeding stalk.
• Pupal period is 7 to 10 days within a whole life cycle period of 26-28 days.

Nature and symptoms of damage

The maggots attack the leaf blades even before uncurling and the initial damage is characterized by the presence of narrow stripes of whitish area in the blade margins. Heavy infestation causes a marked stunting of the plant and reduction of tillers.

Control measures

Chemical

• Apply Phorate 10 G @ 10 kg / ha or Carbofuran 3 G @ 25 kg / ha or spray Fenitrothion 50 EC at 0.1 % (2 ml/lit).
• Apply Carbofuran granules @ 0.75 kg a.i./ha or Fipronil granules @ 75 g a.i./ha.

Economic threshold level (ETL)

• 20 % damaged hills upto 30 days after planting.